1. Technical Field
This invention relates to a method of loading containers in an optimum way on a load-carrying platform of a platform of a vehicle.
2. Prior Art
In case a plurality of containers of the same shape are loaded on a load-carrying platform of a truck, for example, load of containers is often one-sided to the front, rear, right or left side even when loaded in centrally symmetrical placement on the platform due to a difference in weight of cargoes contained in respective containers.
If a vehicle with one-sided load drives, one-sided centrifugal load may work on the platform while the vehicle goes around a curve, and may therefore degrade the stability.
To avoid this, for loading containers in one row in the front-to-rear direction, there is proposed a method of weighting respective containers for evaluating the loading balance and determining the optimum front-to-rear position of containers to optimize the front-to-rear loading balance (Japanese Patent Laid-Open Publication No. sho 59-31223).
This method is directed to loading containers in one row in the front-to-rear direction, and determines the loading pattern such that the sum total of weights of respective containers becomes zero. The containers loaded are equal in weight.
Further, a method of evaluating the balance upon loading cargoes different in shape was invented earlier by the same inventors of the present invention, and it has been disclosed in Japanese Patent Laid-Open Publication No. hei 8-244981.
The method disclosed therein divides the loading space into unit spaces each sized equally to the size of the smallest of cargoes to be loaded, then assigns the weight of each cargo to be loaded to each cargo address corresponding to one or more unit spaces, thereafter calculates its moment, and finally calculates the weight balance ratio of the loading space from that moment.
The prior art of the former publication (Japanese Patent Laid-Open Publication No. sho 59-31223) handling containers equal in weight can load containers such that the sum total of weights becomes zero. This prior art, however, does not teach its application to loading containers different in weight of cargoes contained therein or loading containers in a two-dimensional layout other than the front-to-rear single row, and its applicable range is narrow accordingly.
The latter prior art (Japanese Patent Laid-Open Publication No. hei 8-24981) relates to loading cargoes not uniform in shape unlike containers, and it is therefore compelled to divide the loading space into unit spaces each sized equally to the size of the smallest of cargoes to be loaded and then assign the weight of each cargo to be loaded to each cargo address corresponding to one or more unit spaces. These steps are very troublesome, and this method is not so practical.
Taking those problems into consideration, it is an object of the invention to provide an optimum method of loading containers, which is capable of easily determining the optimum loading balance when loading containers various in weight over front-to-rear and right-to-left dimensions, and is therefore very practical.
To accomplish the object, the invention provides a method of loading containers in an optimum way on a load-carrying platform of a vehicle, in which a plurality of containers identical in shape are loaded in front-to-rear and left-to-right matrix arrangement symmetrically of the platform center, comprising: calculating moment weight Wixc2x7i which is multiplication of total weight Wi of containers in each row distant forward by i rows from the platform center by i; calculating moment weight Wxe2x88x921xc2x7i which is multiplication of total weight Wxe2x88x921 of containers in each row distant rearward by i rows from the platform center by i; calculating the bias load ratio in the traveling direction, which is the ratio of the difference |xcexa3Wixc2x7ixe2x88x92xcexa3Wxe2x88x921xc2x7i| between the total xcexa3Wixc2x7i of moment weights of rows located forward of the platform center C and the total xcexa3Wxe2x88x92ixc2x7i of moment weights of rows located rearward of the platform center C relative to the sum of same (xcexa3Wixc2x7i+xcexa3Wxe2x88x921xc2x7i); calculating moment weight Wjxc2x7j which is multiplication of total weight Wjof containers in each column distant leftward by j columns from the platform center by j; calculating moment weight Wxe2x88x92jxc2x7j which is multiplication of total weight Wxe2x88x92j of containers in each column distant rightward by j columns from the platform center by j; calculating the bias load ratio in the breadth direction, which is the ratio of the difference |xcexa3Wjxc2x7jxe2x88x92xcexa3Wxe2x88x92jxc2x7j| between the total xcexa3Wjxc2x7j of moment weights of columns located leftward of the platform center C and the total xcexa3Wxe2x88x92jxc2x7j of moment weights of columns located rightward of the platform center C relative to the sum of same (xcexa3Wjxc2x7j+xcexa3Wxe2x88x92jxc2x7j); and loading the containers such that the calculated bias load ratio in the traveling direction falls within a predetermined range and the calculated bias load ratio in the breadth direction falls within a predetermined range.
Therefore,
Bias load ratio in the traveling direction =|xcexa3Wixc2x7ixe2x88x92xcexa3Wxe2x88x92ixc2x7i|/(xcexa3Wixc2x7i+xcexa3Wxe2x88x921xc2x7i)
and
Bias load ratio in the breadth direction =|xcexa3Wjxc2x7jxe2x88x92xcexa3Wxe2x88x92jxc2x7j|/(xcexa3Wjxc2x7j+xcexa3Wxe2x88x92jxc2x7j
Therefore, once the weight of each container (weight of cargoes contained therein and own weight of the container) to be loaded is input, respective total weights of containers Wi, Wxe2x88x921, Wj, Wxe2x88x92j and respective moment loads Wixc2x7i, Wxe2x88x92ixc2x7i, Wjxc2x7j, Wxe2x88x92jxc2x7j are readily determined, and the bias load ratio in the traveling direction and the bias load ratio in the breadth direction can be calculated from the above equations.
With the method according to the invention, containers may be loaded such that the bias load ratio in the traveling direction and the bias load ratio in the breadth direction obtained by the calculation fall within predetermined ratios, and the load balance condition can be easily confirmed to be acceptable or not. Therefore, the method is convenient and very practical.
In the method of loading containers in an optimum way on a load-carrying platform of a vehicle according to the invention, i=0 or j=0 may be assumed for calculation of containers in a column or row that coincides with the center of the load-carrying platform.
When containers are loaded in odd number rows or odd number columns, the central row or column coincides with the platform center. Then i=0 or j=0 is assumed for calculation.
That is, the row or column coinciding with the platform center may be regarded not to exist for calculation.
In the method of loading containers in an optimum way on a load-carrying platform of a vehicle according to the invention, containers are preferably loaded such that the bias load ratio in the traveling direction is limited approximately within 8% and the bias load ratio in the breadth direction is limited within approximately 4 percent.
If the bias load ratio in the traveling direction is within approximately 8% and the bias load ratio in the breadth direction is approximately within 4%, the loading balance is good, and a vehicle with containers loaded in this condition does not lose stability even when a centrifugal load is applied to its load-carrying platform while it runs along a curve.